(a) Field of the Invention
The invention relates to an image processing system for image data in endoscopy, which is especially useful for surgical purposes but may also be used in general technology.
(b) Description of the Related Art
Such image processing systems in the form of digital endoscope cameras are in use both in general technology with respect to hardly accessible repair positions—as well as in minimally invasive surgery. Due to the short focal length of the cameras, a relatively large depth of field is provided, which is necessary to provide a good overview of the workspace. So the objects under inspection do not get out of focus with a displacement of the endoscope. The cameras have a fixed focus which is adapted to the working area. The depth of field in known systems may comprise a distance from 1 mm to infinity.
The objects under observation and in focus within a working area may be located at different distances from the camera front lens. The size of an object displayed on the monitor is difficult to evaluate if there are no close objects of known size available in the picture.
The system known from U.S. Pat. No. 7,206,006 B2 for representation in actual size by means of a digital camera and a corresponding display may not be used for the intended application. A pre requirement for the known system is a fixed distance between the object and the lens of the camera. Furthermore, frame synchronization pulses have to be inserted in the picture as a size reference. It is apparent that these reference pulses do not change with the distance of the object—and therefore with the reproduced size. With the variation of the object distance the reproduced object changes in size, without any recognition of the change of scale, because the number of frame synchronization pulses is not varying accordingly.
A quite different situation is to be found in picture representations in medical technology gained by direct X-ray radiation or by computer or Nuclear Magnetic Resonance Spectroscopy. Here the scale is already set by the picture geometry used (which may be natural scale). This indeed provides processes for the virtual adaptation of implants to the patient, for example in dentistry. An example is shown by VIP Virtual Implant Planning, at: http://www.virtual-implant.de/simulation.html (available date of priority). Here are three dimensional image representation renderings of CT and implant are fitted by manual selection, overlaying and spatial displacement. This method therefore is also unsuitable for the above-described problem. In addition, the imaging, the selection of the implant, the orientation and assessment by the operator has to take place remote from the working field and is time consuming. That is why the known procedure may not be used during surgery. The same applies to a planning software for dental implants, http://www.materialise.com/materialise/view/en/131410-SimPlant.html, that has also been accessible before the application's priority date.
From EP 1778094 B1 an endoscopic video measurement system is known, by means of which light points in the range of the object may be generated to carry out measurements within the image representation. This measurement is performed by manual selection of suitable points and the subsequent determination of the scale by means of selected distances measured within the image representation. Subsequently a detail in the image representation is selected, whose dimension is to be determined. After having determined measured manually the relevant details in the picture, its dimensions may be calculated on the basis of the scale factor and the unit of measurement selected. The Dimensions of an implant or repair element to be introduced to the field has also to be known to fit. The fit may be judged only on the basis of the two metrics. This procedure is cumbersome and unsuitable for a rapid handling during surgery.
The foregoing system may be used appropriately in the event of medical imaging, as described in http://www.efims.de/de/meetinRs/hnod2009/09hnod324.shtml. According to this method by means of manually determined distances defined by the laser markings the volume of the object may be estimated. This procedure is also time consuming and therefore cannot be performed during surgery. In the known solution is the image representation scale on the monitor stays fixed. That is why a direct comparison with a physically present object or an image representation stored as a reference element in a fixed scale is not possible.
In a system describe in U.S. 2007/0065002 A1 by means of which a recorded 3D laser scan data model may be updated with 2D image representations is also not giving any evidence.
In JAHNKE, M. 3D exploration of volume data, thesis, Univ. Bonn, 1998, general tools for subsequent interactive exploration of medical image representation data are described. Notes respective to image representation reproduction in scale during surgical application do not apply.
In the lecture notes VORNBERGER, O., MUELLER, O.: Computer Graphics, Univ. Osnabruck, S S 2000, the basics of in computer graphics are described. There is no evidence with respect to present problem.
In JERAMIAS.RF: CMOS image representation sensors with short-term closure for depth sensing the principle of light transit time measurement and a method for measuring distances according to the light transit time principle is described. This kind of distance measurement however is not of direct relevance in connection with the aforementioned problem.
In GRIONI, C. Digital photography, Diploma Thesis, Univ. Graz, 2007, the Sony Smart Zoom principle is described, by means of which a digital zoom is limited to a selected resolution in order to maintain a desired playback quality. This solution also is not relevant to the problem discussed here.